Quiz Entry - updated: 2026.07.14
What is PRESENT and why is it significant for IoT?
PRESENT is an ultra-lightweight block cipher designed for resource-constrained devices (IoT, RFID, smart cards) with only 64-bit blocks and 80 or 128-bit keys.
Parameters:
| Parameter | Value |
|---|---|
| Block size | 64 bits |
| Key length | 80 or 128 bits |
| Rounds | 31 |
| Gate count | ~1,000 GE (serial implementation) |
Why it matters:
- AES requires ~2,400 GE — too much for tiny devices
- PRESENT achieves security with less than half the hardware footprint
- Approaches the theoretical minimum of ~800 gates
- Standardized as ISO/IEC 29192-2 (lightweight crypto standard)
Design:
- Substitution-Permutation Network (SPN), like AES
- Very simple round function: S-box layer → bit permutation → key addition
- Designed for hardware efficiency, not software speed
Use cases: RFID tags, sensor nodes, embedded systems, smart cards — anywhere gates and power are extremely limited.
Tip: "PRESENT = tiny AES for tiny devices" — same SPN concept but radically simplified for minimal hardware.
Go deeper:
PRESENT (Wikipedia) — the ultra-lightweight SPN standardised as ISO/IEC 29192-2.